1. Field of the Invention
The present invention relates to an improved device for coupling with and tapping a keg of beer and for pressurizing it using a pump.
2. The Prior Art
To tap a keg of beer or similarly packaged beverage, a coupler is screwed into a valve assembly in the container through use of thread-like mating cams and lugs. A probe at the insertion end of the coupler depresses the valve mechanism, typically a spring loaded ball valve, permitting the flow of pressurizing gas and the flow of beer or other liquid. A suitable tap, that is, a dispenser, is attached to the distal end of the coupler.
Two general types of couplers are currently in widespread use. One is a commercial coupler, which uses pressurized carbon dioxide gas, typically bottled, to pressurize the keg. The other is a consumer coupler, which uses an air pump, that is a hand-powered compressor to pressurize the container. The consumer coupler is more readily portable and is therefore commonly known as a picnic coupler and pump system.
A typical commercial coupler is described in U.S. Pat. No. 4,181,143, issued to Fallon. The coupler includes thread-like cams at its lower face, which are accommodated by mating lugs on the inner circumference of the of the container opening adjacent the valve assembly. Then, by a separate action, a handle or cam actuates a movable probe inside the coupler, which pushes against the ball valve assembly and thereby permits the flow of fluid into and out of the container through appropriate channels. The probe, which forces the ball valve away from its seat, moves relative to its surrounding cam, which secures the coupler to the container. This type of coupler and dispenser requires use of an external and bulky source of gas to pressurize the container. The commercial coupler, however, also enjoys significant advantages, which include: widespread consumer acceptance, in both commercial and consumer practice; and a sturdy mechanism that does not usually leak and is long lived, even in the face of hard use.
In a conventional picnic pump system, the coupler is inserted by rotation into the valve assembly in the same manner as the commercial coupler. This compatibility is virtually required because nearly all beer kegs use the same standard coupling system. After the consumer coupler is secured to the container, a second rotating action rotates a movable probe, causing it to move into the container and to push the ball valve off its seat, permitting fluid to flow into and out of the container through appropriate channels. This type of consumer coupler may leak around the probe and locking cams. Consumer couplers having a fixed probe are also known in the prior art, as illustrated by U.S. Pat. No. 4,520,954, issued to Brown. In this type of consumer probe, the probe head protrudes from the coupling cams of the coupler, so that the probe head engages and opens the ball valve in the container before the coupling cams of the coupler are fully engaged with the coupling lugs of the container. Naturally, this leads to leaking of the fluid from the container, which typically is under pressure prior to opening of the valve. A flexible bellows-type seal around the circumference of the coupler reduces the leakage associated with tapping a pressurized container with this type of coupler. Such couplers are, however, not widely accepted by the consumer since they may appear to be less sturdy than commercial couplers and they tend to leak occasionally.
Therefore, a significant need exists for a coupler and dispensing system that combines the advantages of the commercial coupler and the consumer coupler, resulting in a coupler and pump that is familiar and therefore easy to use, does not leak, is readily portable, and is long-lasting.